Early 1974 260z build

[juggernautjoee]

Getting a little farther along.

 

I took as many pictures as I could along the way, but a lot of things were either plugged up, not hooked up, or broken.

 

So I'm using the FSM to identify as much as I can.

 

I do have a couple of questions, if someone can answer, great.  If not, I'm sure I'll figure it out later.

 

In the attached picture, is the blue circled port the anti-backfire? 

 

What ported vacuum port do people use for the distributor?

[Noll]

Not sure how much of this may be applicable, as my 260z has 240z carbs swapped on and all the smog/anti-backfire/etc stuff deleted, but here's how it is on my car:

 

I ran the vacuum advance to the port on the front carb, would be easy to just slap a T-fitting in there if that's already occupied in your case. that and the brake booster are the only things using vacuum in my case (the line ziptied to my re-located breather hose just has a bolt in the end and goes nowhere, was the cleanest way I had to block that one off at the time).

 

It's been a hot minute since I looked into it but I BELIEVE that you want the advance getting vacuum from one of the carbs directly as hooking into the balance tube can cause way too much advance.

 

My setup probably also looks a bit funky because of the aforementioned carb breather stuff; as I don't have the stock airbox I decided to go overkill and route the breathers all the way around to the p/s of the block so they wouldn't be dumping gas on the exhaust manifold if they did overflow.

Edited February 17, 2022 by Noll

[juggernautjoee]

Thanks, that helps.

 

Yeah the ported vacuum port is right behind the left carb.  I didn't see it initially.  Mine was blocked off.

 

 

[juggernautjoee]

Got it running.  Had to advance the timing a touch and turn the jet screw down to fatten it up.

 

Dialed in the timing to the 10 degree mark as a start.  

 

Got good oil pressure.

 

Clutch works, wheels spin in gear.

 

Need to read up and research a bit on setting idle and tuning these carbs right.  If I give it a quick throttle blip, it'll backfire and die.  But it feels good to have a running motor now.  Just gotta dial it in.

Edited March 3, 2022 by juggernautjoee

[juggernautjoee]

Only got 10in of vacuum off of the brake booster port on the intake.  So definitely had some vacuum leaks to hunt down.

 

Sprayed brake clean on various ports and surfaces.  Found a couple of loose intake bolts that I must've missed.  Also, there was a bit of leak around the crossover pipe on the intake.  I took the crossover off, and the gaskets had some kind of clear/blue silicone on them.  Someone must have tried to just jam it in there to stop the leak.  I've got a couple of new gaskets on the way.

 

Also slapped some thermal tape on the fuel rails.

 

 

[juggernautjoee]

Well.  It only likes to run if I choke it manually with my hand on the front carb.  The rear carb seems to run fine.  Choking it doesn't really help.  

 

So I know that means I'm basically enriching the mixture to make it run better.  So that means either fuel isn't getting out of the jet properly, or there is a vacuum leak farther down.  So I went into both carbs and lowered the adjustment "tab" on the float bowl to force it to fill up a bit more.  I set these originally by blowing through the fuel line and getting the needle to close right when the float itself is parallel with the bowl.  I may be mistaken, but that should be good enough to get started.  However, moving the tab down to increase the float level didn't really do anything.  Looking down the carb I can see gas, but it's pretty far down the hole.

 

I double checked timing, it's set fine at 10deg advanced.  

 

Fast idle screw was removed when I took the EGR off.  I'll need to rig up some kind of bracket for that.

 

The individual idle screws were set to 1 turn in from the point where it first contacts the throttle.  Each carb was set individually without affecting the other.  I tried increasing the idle a bit on the front carb to see what that did, but didn't help much.

 

Bad news is that I'm 100% certain the throttle shafts are leaking like crazy.  A shot of starting fluid on them increases rpm/vacuum tremendously.  But I can't find any other leaks.

 

So now I have to think about taking these carbs back apart to clean them, send them out, buy some other ones, or try and get this FI intake to work.  I know i'll need a harness and some sensors for that.  I don't know if that route would be the most beneficial.

[bunkhouse]

Here's the simplest method for checking float levels I've found. The fuel level should be 3/8" below the carb bridge. Remove the carb domes and pistons. Turn the mixture screws and raise the jets to their top position. Now turn the mixture screws 9 1/2 - 10 turns down. (9 5/8 turns is 3/8") The fuel level should be close to the top of the jet. It doesn't have to be exact, close is good enough. Re-adjust the mixture screws to app. 2 1/2 - 3 turns down from their uppermost position.

[juggernautjoee]

Ok I'll try that first.

 

Next thing I'm gonna do is find some flat metal or rubber and basically make block-off plates for the intake crossover pipe.  Just to eliminate that as a leak.

 

Then I'll try to find something to block off the throttle shafts a bit to see what that does as well.

 

I've had to track down vacuum leaks in the past on several vehicles.  Just gotta block things off one at a time to find the source/s

Edited March 11, 2022 by juggernautjoee

[juggernautjoee]

My jets don't seem to turn down more than 7.5 turns.  They stop after that.  

 

I tried blocking off the cross over, and I couldn't even get it started.  Put the cross back on, it starts again.

 

There is also some loud squeals coming from the rear of the block.  Sounds like a cam lobe or rocker might be burnt out.

 

This just keeps getting better and better lol

[Sanchez]

I had a similar problem with my SUs after getting them back from ZTherapy, who did an excellent job. And my issue was fuel routing, the FPR I was using wasn’t properly marked (2 outlets and a return) and I had accidentally plumbed the back carb into the return so I had to run it pig rich to get it idling decent. I can’t see your entire fuel line plumbing, but I see you have the float bowl vents tied into the return line. They normally vent to the filter housing which would be at atmospheric pressure. It might be worth trying venting those to your filters if it has provisions for it or atmosphere, and plumb the FPR return directly to the return hard line on the passenger side.

Edited March 11, 2022 by Sanchez

[bunkhouse]

3 hours ago, juggernautjoee said:

My jets don't seem to turn down more than 7.5 turns.  They stop after that.  

 

 

There's a flat stop screw on the bottom that can be removed. It prevents the mixture screws (jets) from being removed.

[juggernautjoee]

4 hours ago, Sanchez said:

I had a similar problem with my SUs after getting them back from ZTherapy, who did an excellent job. And my issue was fuel routing, the FPR I was using wasn’t properly marked (2 outlets and a return) and I had accidentally plumbed the back carb into the return so I had to run it pig rich to get it idling decent. I can’t see your entire fuel line plumbing, but I see you have the float bowl vents tied into the return line. They normally vent to the filter housing which would be at atmospheric pressure. It might be worth trying venting those to your filters if it has provisions for it or atmosphere, and plumb the FPR return directly to the return hard line on the passenger side.

 

I actually don't have a FPR.  It's just a new electric pump going straight to the fuel feed line.  Then those 2 go into the bowls.  My bowl vents are open to the atmosphere right now.  I'm pretty sure I have the fuel feed line hooked up right.  The return hard line has a very small opening (I assume to keep pressure in the system near the carbs).  

 

 

1 hour ago, bunkhouse said:

There's a flat stop screw on the bottom that can be removed. It prevents the mixture screws (jets) from being removed.

 Ah I'll have to take a look at that.

 

So I took the valve/cam cover off just to see if what I expected was true.  And yep, I made a big mistake.  I put my externally oiled original camshaft in this newer N47 head.  This head didn't have provisions for the oiler bar, but I saw the holes in the cam towers and assumed the original camshaft would work.  Wiped out the lobes pretty good.  Rockers were bad too.

 

Luckily I have that spare cam and rocker set that I'll throw in here.  Now I get to relash all the valves again.

 

 

Edited March 11, 2022 by juggernautjoee

[juggernautjoee]

Well it runs 100% better now that the cam is actually opening valves correctly lol.  Such a dumb mistake, but it happens.

 

I'll get around to doing the hot lash valve adjustment this week when it isn't 23 degrees outside.

 

I have to turn down the jet all the way rich for it to run though.  I removed the little screw and bracket to hopefully let it drop more to do the "10 turns" trick to set the float.  But I also seem to have this stopper bracket that isn't allowing to be screwed down anymore.  I tried turning this stopper by hand, but I think I'll need to take the carb off to remove this thing.

 

 

I am hopefully going to make a deal on a set of some rebuilt SU's and linkage tomorrow.  So I'm going to focus on bleeding the brakes/clutch with my power bleeder. 

[juggernautjoee]

Been a couple months.  I'll try to get some pictures of what I've been working on.  But here is the list so far:

 

Polished all the oxidation off, so now it has a bit more red to it.

All new rear brakes (machined the rotors, shoes, cylinders, etc...)

Had to clean out the turn signal, headlight, and hazard switch connectors.  All electrical seems to be working so far.

Seat recliners fixed with some penetrating spray

Installed a 280zx non-turbo dizzy to get rid of the ballast resistor and get a stronger spark

Front diff mount replaced with a solid one

 

Next up are wheels and tires.  But before I do that, i went ahead and got a poly bushing kit, new tie rods and ball joints.  I want to get the steering/suspension squared away first.

 

So one weird thing I noticed is that my front strut tube diameter is 55mm, and my rears are 51mm.  I'm supposed to have an early build 74 260z, so I thought I'd have 51's front and rear.  Guess someone decided to put 280z spindles/struts in the front?  That's going to make it a fun endeavor to get a set of coilovers for this thing.  

 

I guess I'll have to either source a set of used strut tubes/spindles from either year and make them match on my car, or go for the super expensive techno toy all-in-one type deals.

[juggernautjoee]

Update:

 

Got the BC coilovers installed, subaru r180 with LSD, all poly bushings, new wheels and tires, sound deadened and new carpet, and probably a few other things that I'm forgetting.  

 

Drove it to a few car shows and did some weekend cruising.

 

But now I've decided to slap those turbo/efi parts on and go Megasquirt over the winter.  I've already ripped off all the carb related parts and most of them are sold.  Can't go back now lol.

 

 

[juggernautjoee]

I took the time to de-web the turbo intake, plug some holes and paint it.  Also painted the exhaust manifold and wrapped it.  

 

 

I also decided to paint the drivers side of the block while I have everything off.  I found a decent color that sort-of looks like the Nissan blue.  Well I thought it did from the can.  It sprayed a lot brighter.  Maybe it'll dry darker.  We'll see.  Yeah it's not engine enamel, whatever.  I'll clean up the overspray with some mineral spirits.

 

 

 

Edited December 11, 2022 by juggernautjoee

[juggernautjoee]

So my plan is to attack this in little mini-projects, with leaving the Megasquirt install for last (if possible).  To give me more time to save up or buy some things first that I'm contemplating on.  

 

First thing is oil.  I'm going to drill a small pilot hole in the oil pan, hammer a plumb bob in to get the hole about where I want it, then hammer in a socket (or something) that is exactly 1/2in diameter to get it straight.  Cut some threads, throw a threaded barbed fitting in, and be good.  Probably need some thread sealant too.  Obviously I'm going to change the oil right after this and throw on one of those stronger oil pumps.

 

I've got all the fittings and lines for the oil feed.  Not sure if I need to worry about an oil cooler right now.  Oil cooler kits are fairly cheap and if/when I decide to turn this thing up, I'll worry about it then.

 

Once that is done, next is fuel.  I know I need a fuel pump, and bigger fuel lines. I can use the stock feed line as a return and just use the drain plug orifice as a feed with some fittings.  Probably run a new AN line up front for the feed.  But the one thing I need to decide on is whether to try and use the stock injectors and rail I have, or go with an aftermarket one.  I can't read anything on these injectors to tell what they are, and one of them appears to be different than the other.

 

A pallnet fuel rail and injectors + a decent FPR is going to be north of $500.  I have N47 head with dished pistons, so I know I'm not going to be able to run a ton of boost until I drop my comp. ratio with a new head.  I'd like to get it running with some cheap stock injectors, then switch up the fueling when I find a P90 head.  Also an intercooler, as right now I'm planning on just using the J pipe.  

 

I know the best thing would be wait until I have the head I want, but I could be waiting around all winter for one.  And I know that it's better to get a car back on the road so you can actually enjoy it instead of it just being a perpetual, never ending project.

 

Then finally comes the MS install itself.  I plan on going with the new crank angle sensor and LS coils.  Of course if a 280zx turbo dizzy and oil shaft show up on marketplace for a decent price, I might snag that up.  But they're rare.

 

Edited December 11, 2022 by juggernautjoee

[calZ]

Did you go poly on the tension rod as well? That has been shown to cause cracking for some people 

[juggernautjoee]

So I did one half rubber, the other half poly

 

I think I put the poly on the outside and rubber on the inside.

Edited December 11, 2022 by juggernautjoee

[calZ]

Ah ok. Nice work. You should be good then.